Lassa fever
It causes viral
hemorrhagic fever.
The reservoir is multi-mammate
rat. The excreta from these rats contains infectious
viral particles.
Contact with rat, or
eating the rat facilitates transmission.
Person to person
transmission is via contact with body fluid such as blood and urine.
The virus is endemic
in countries of West Africa and
Seroprevalance rate
could be as high as 50 % in some communities.
Good infection control
measures in hospitals seating is important to prevent outbreak.
High fatality
Ÿ
Children
Ÿ
Pregnant
mother especially at third trimester
Ÿ
Neonates
Ÿ
Viraemia
Ÿ
High level
of transaminase
Incubation period ranges between 6-18 days.
Clinical
Presentation
Asymptomatic or mild
infection is common
Most patients present
with acute febrile illness.
Fever, painful sore
throat, sever headache and retrosternal pain is
common.
Vomiting
and diarrhea.
Hypotension,
facial edema.
Mucosal
bleeding (mouth, nose, eye).
Internal
bleeding.
Convulsion,
coma and death.
Mortality rate is 1-2
% however in hospitalized patients it is as high as 16 %.
Immunity is life long.
Investigation
Laboratory results
Blood film should be
done to exclude malaria.
Lymphocytopenia and moderate thrombocytopenia is common.
U/A- proteinuria
Complications
Tests
Specimens- clotted
blood, blood in EDTA, and Urine.
Serology- most
patients have detectable level of IgM
at admission
PCR- has high
sensitivity. It should be repeated if negative in the first 3 days of illness.
Management
General support- fluid
balance
Ribavirin po or IV
should be given in the first 5 days of illness.
Infection
control measures is very
important.
Strict isolation is
required to prevent person to person transmission.
Proper
handling of body fluids and appropriately disposal of excreta.
Prophylaxis Ribavirin can
be given to contact at high risk of acquiring infection .
Prevention
In hospital setting,
strict isolation is necessary to prevent outbreak. Even after recovery, virus
particles can be found from body fluids. The virus has been detected in semen
even after 3 months of recovery; it is however not clear whether sexual
transmission plays an important role.
There is no vaccine.
Travelers to area
where Lassa fever is endemic should avoid contact with rat.
Public health measures such as controlling the population of rat in communities are important.